Biometric recognition systems generally involve recognition of a person by presentation of some physical characteristic of the person to a machine. These systems have been shown to have value in various security applications including facility access control. Biometric recognition based on hand or palm characteristics has been proposed in a number of prior art references.
Kondo U.S. Pat. No. 4,206,441 discloses a palm pattern detector system and discusses various approaches to hand feature extraction. The system of the Kondo '441 patent utilizes a two dimensional image of the person's hand.
An SRI International Technical Report entitled "Automatic Palmprint Verification Study" by Young & Hammon (RADC-TR-81-161) dated June 1981, discusses approaches to hand feature extraction based on a two dimensional image of the hand.
Shuto U.S. Pat. No. 4,573,193 discloses the use of guide means to assist in reproducible positioning of the hand of the person being measured by the apparatus.
Sidlauskas U.S. Pat. No. 4,736,203 discloses a three dimensional hand profile identification apparatus. A pair of orthogonal retroreflecting surfaces are utilized to present concurrently a plan view and a profile view of a human hand to an imaging system. The addition of a profile view affords the opportunity to extract additional hand feature data, but it consists of an overall hand profile as the third dimensional image and does not provide any basis for extracting a third dimension of feature information on individual fingers.
A commercial version of the Sidlauskas system offered by Recognition Systems, Inc. of San Jose, Calif. is sold under the trademark "Handkey." The Handkey system also uses hand positioning guides on its retroflective platen to aid in reproducible finger positioning during both the hand enrollment operation cycle and the hand bid operation cycle.
Hand enrollment involves performing an initial measurement on a person's hand and storing the hand feature data extracted as hand enrollment data. Hand bidding involves a subsequent presentation of the person's had to the machine and the hand feature data extracted during the hand bid operation cycle is hand bid data. The machine compares the hand bid data with the hand enrollment data to decide if the same hand was used to produce both sets of data. Typically the hand bid operation cycle also involves manual input of some identification data by the person doing the bidding, such as entry of a PIN code on a keypad or swipe of a magnetic data card through a card reader.
While the Handkey system has proven its effectiveness in various security applications, there is need for further improvement in the discrimination ability and corresponding accuracy of biometric measuring apparatus of this type.